Since the mid-1990s, divers have been uncovering the ruins of ancient Alexandria, which was destroyed and submerged by an earthquake more than 1,000 years ago. This past December came breathless news reports that a team led by Alexandria-born Greek historian Harry Tzalas had recovered columns and sculptures that belonged to the Temple of Isis or even Cleopatra’s palace.

But Emad Khalil, director of the Alexandria University Centre for Maritime Archaeology & Underwater Cultural Heritage, says there’s no evidence to link the stones scattered on the ocean floor with specific historic buildings such as the palace of Cleopatra. Nearly 400 years passed between Cleopatra’s suicide in 30 B.C. and the A.D. 365 earthquake that submerged ancient Alexandria’s coastline. Four centuries of Roman rule changed the city dramatically, from the capital of Egypt to a province of Rome.

“Without clear evidence like an inscription or a name somewhere, it’s quite difficult,” Khalil says. The previously identified remnants of the Lighthouse of Alexandria are an exception. The massive 70-ton stone blocks Khalil says “couldn’t have come from anywhere else.”